Two electricians who survived the Kleen Energy power plant explosionin Middletownhave filed the first lawsuit against the contractor conducting the gas line purge that claimed the lives of six people and injured 26 others.

While some of the victims headed to court and investigators continued trying to piece together whether criminal charges would be filed, the national board that sets regulations for gas purges was prepared to discuss the tragedy at a meeting later this week in San Francisco.

The lawsuit, filed at Superior Court in Hartford by Timothy Hilliker and Harold Thoma, who both were working for Ducci Electrical Contractors Inc. of Torrington, alleges that the Feb. 7 purge was poorly supervised, that active welding and grinding were taking place on-site at the time of the explosion and that a gas-fueled torch heater was running at the time of the deadly blast.

"These guys showed up to work and had no concept of what was going on," said New Haven attorney Joel Faxon of Stratton Faxon, the firm representing the two men.

"There was no supervisor telling them what to do," Faxon said.

Faxon said that Thoma had just stepped out of the Ducci construction trailer when the blast occurred. He suffered head injuries and has been in and out of the hospital. Hilliker was in the trailer when the blast occurred and was thrown into a wall; he also had head injuries.

Faxon said his firm represents about 12 people who were working at the plant when the blast occurred. The lawsuit names O&G Industries, the general contractor for the billion-dollar construction job; Keystone Construction and Maintenance Services Inc., which was supervising the purge; and plant owner Kleen Energy Systems LLC.

Contractors were in the process of pumping nearly 700 pounds per square inch of natural gas through pipes when the explosion took place in the "courtyard" area between the two giant towers behind the power block building. Sources familiar with the investigation have told The Courant that on the final and largest purge, the gas was vented out of pipes into the courtyard area, creating a giant pool of natural gas that had nowhere to disperse.

The six workers who were killed were all working near one of the gas turbines in the back of the building, near a garage door leading into the courtyard. They were blown out of the building by the force of the blast.

Three of the men — Raymond Dobratz, 58, of Old Saybrook; Ronald Crabb, 42, of Colchester; and Peter Chepulis, 48 of Thomaston — were on the startup crew working for Keystone. Two others, Chris Walters, 48, and Kenneth Haskell, 37, were also Keystone employees: Walters was the safety manager and Haskell the superintendent. Roy Rushton, 36, was a supervisor involved with the installation of the gas turbines at the plant.

The explosion at Kleen Energy — among the country's worst industrial disasters in the past few years — is on the minds of regulators and combustion engineers throughout the country.

The pipeline purging that led to the blast is expected to be discussed at a National Fire Protection Administration safety meeting in San Francisco on Wednesday, and during a separate national Web seminar on gas-purging safety next week.

"You read about the loss of life, the disruption, the destruction, from these incidents. We want to be able to do something of value," said Bryan Baesel of Combustion Safety Inc., the Cleveland-based company sponsoring the Web forum.

Baesel and other engineers participated in a safety-code review after a natural gas explosion at the ConAgra plant in North Carolina killed four and injured 67 people last year. Just three days before the Middletown explosion, the U.S. Chemical Safety Board issued urgent safety recommendations stemming from the board's probe of the ConAgra blast.

The safety board is also investigating the Middletown blast and is participating in the NFPA conference.

The NFPA meeting had been scheduled to take up the chemical board's ConAgra recommendations. While the North Carolina and Middletown explosions are different — one occurred at a factory at relatively low gas-line pressure; the other at a power plant at a very high pressure — "the overarching safety concepts are similar," said Dan Horowitz, a spokesman for the Washington-based chemical safety board.

"You don't want to ventilate in an area where gas can accumulate near people and ignition sources," Horowitz said. The board is recommending a ban of indoor purging of gas lines and says that gas should be discharged outdoors, away from all confined areas.